can you describe your Client user interface, did use MVC pattern?
Sure. I did use the MVC pattern, as you pretty much have to in order to use Swing properly.
The GUI was built dynamically based on the properties file to determine which fields were searchable. Each searchable field was an editable combo box that stored the last searched for terms in it's list. These terms were stored in the properties file for persistance between run sessions.
In order to book a room you double clicked on the field (or pressed F2) and entered the customer #. Any errors were displayed in a status bar at the bottom or a dialog box, whichever was most appropriate.
I thought it was really nice and usable, clear and simple, myself, but I got a relatively mark on the GUI, so I wouldn't use it as an example